A Schmidt Servo Press with special tooling forces open a springoperated latch to measure the force and distance needed to push the latch fully down, part of the quality assurance process at latch maker Hatch Stamping.

A Schmidt Servo Press with special tooling forces open a springoperated latch to measure the force and distance needed to push the latch fully down, part of the quality assurance process at latch maker Hatch Stamping.


Engineers at Hatch Stamping, Chelsea, Mich., designed a floormounted seat-belt quick connect for a major auto company. The mechanism is made up of seven or 11 components, depending on the model. Hatch engineers also designed an assembly process for the latch with Schmidt Technology Corp. in Pittsburgh.

During assembly, a nonsynchronous conveyor moves parts past different stations, including an inspection station. This station visually verifies all parts are present and that they meet quality standards before moving through two rivetstaking operations performed by Schmidt presses. Prior to a final visual and mechanical inspection, a Schmidt Servo Press module head unit and pressure controller measure and qualify the latch.

Each latch must be tested and the results documented. "Obviously, the latch and the buckle cannot fail during a crash," says Ron Hogbin, an engineer at Hatch. For testing, the Servo Press pushes on the latch pawl, forcing the springoperated latch down while the press measures how much force and distance it takes to fully depress the latch. The press also records return travel of the pawl to ensure the spring returns to its proper height under tension. A display lets an operator quickly verify that force and distance fall within tolerances.

"Fault conditions are detected by vision systems and automated mechanical gaging tools, while the Servo Press does the verification," notes Chad Peltier, a Hatch engineer. Inspections detect stamping variations, missing and misaligned parts, and whether latches are too weak or too stiff due to the wrong spring-steel strength. Three rejects in a row, or five out of 100, shuts down the assembly machine.

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